1. Field of the invention
The invention relates to a device for separating and filtering particles in a flow of fluid, and is particularly applicable to the separation and filtration of solid particles in a metered fuel supply to a turbomachine.
2. Summary of the prior art
In numerous devices which operate with highly pressurized liquids, it is necessary that the liquid should be perfectly filtered in order to avoid wear caused by contaminants in the liquid. It is current practice to comply with this requirement by using a filter cartridge which can be replaced when clogged. It is also current practice to fit a bypass valve which enables the liquid to keep flowing by avoiding a clogged cartridge. The condition of the filter must therefore be regularly checked in order to avoid rapid deterioration of the expensive equipment which the filter is intended to protect.
In the particular case of a turbomachine fuel supply and metering system generally comprising a gear pump, for example of the proportioning type, a flow metering device and fuel injectors, it is necessary to protect the system from external contamination originating from the fuel tanks, and to protect the metering device and the fuel injectors from contamination due to particles produced by wear or deterioration of the pump. However, it is not possible to achieve this double protection by using only one filter. Moreover, using two filters sited one upstream and one downstream of the pump leads to installation difficulties, an increase of the mass of the engine, additional maintenance operations, and operational difficulties due to the considerable pressures downstream of the pump. Furthermore, these systems introduce noticeable pressure drops which increase according to the degree of clogging of the filter.